Manufacture of acetylene



v Hydrocarbon July 10, 1934- H. P. A. GROLL ET AL 1,955,771

MANUFACTURE OF ACETYLENE F/amc 77p, 6

Oxy; en ase of H12/77 A, 2 C

F/dme 77,0

gli

July 10, 1934. H. P. A. GROLL ET Al. 1,965,771

MANUFACTUBE oF ACETYLENE FiledApIil 24, 1933 2 Sheets-Sheet 2 /7 ydraad/*bon Hydro cof-bon 043/9 ef; g 0x y gen ,5y me AW Patented July1o, 1934 UNITED STATES monomer. or AcE'rrLENE Herbert Fetal-AugustusGroll and Jam Oakland, Calif.

vApplication April 24, 1933, Serial No. 667,159? f l2 Claims. (Cl.260-170) In a copending application, Serial No. 567,300, led October `6,1931 by James Burg'in, is described the production of acetylene by theincomplete combustion of mixtures of hydrocarbon and oxygen by an gasvelocity greater than the velocity of llame propagation. We havediscovered that we can produce at least as good yields of acetylene fromgaseous mixtures possessing an gas velocity less-than, equal to orgreater than the flame velocity by utilizing a portion .of the llameproper to maintain llame combustion.

, Hydrocarbons such as parailine hydrocarbons, olenne hydrocarbons,aromatic hydrocarbons, naphthenes, natural gas, casinghead gas vapors,industrial gases containing hydrocarbons, etc. are subjected toincomplete combustion with oxygen, air or an oxygen-containing gas at orabove the ignition temperature of the gaseous mixture, while maintainingilame combustion.

While the initial gas velocity may be equal to, less than or greatervthan the ame velocity, the gas velocity is always greater than the amevelocity during the main production of acetylene and during this periodflame combustion is main-- tained in an enclosed apparatus by using partof the flame proper. In other words, we provide a comparatively smallsection of flame at the base in which the gas velocity does not exceedthe llame velocity. This portion allows the maintenance of a flamealthough the main portion of the combustion takes place in a section ofa chamber in which the gas velocity is essentially ,higher `than theflame velocity of the mixture. There are several arrangements possiblewhich create a slower gas velocity in a portion of the combustion spacesituated at the base of the ame and reference will be had to theembodiments illustrated in the drawings merely to supplement thedescription in the speciilcation. 1

Figures I, II, and III illustrate views partly in section, and partly inelevation of various arrangements adapted to carry out the process,while v Figures IV, V, VI, and VII illustrate ows and shapes of burninggas mixtures in sectional elevation.

Where the initial gas velocity is less than, or

equal to the flame velocity, it is desirable to in crease the gasvelocity after the gaseous mixture has been ignited, at the same timemaintaining flame combustion in the enclosed apparatus. This conditioncan be attained by constricting the volume of the gaseous mixture.Conning the ame to a smaller volume serves to concentrate the evolvedheat and raises the .concentration of acetylene.

Figure I illustrates a simple arrangement. A combustion chamber consistsof one wide.section 1 and one narrow section 2. The b urner face 3 is 60situated in the wide section and a llame 4 burns from the burner facewhich is made of metal screen or consists of a great number of smallnozzles, or otherwise is designed so that the ilame cannot backfire intothe gas device 5.

Thisflame, if allowed to burn to completion in a long enough sectionofythe same width as the flame base, would assume the well-knownconelike flame shape, as for instance, can be observed on a Fischerlaboratory burner. However, inthe .70

apparatus used to carry our invention into practice, the wide portionofthev combustion space extends, preferably, only for such a distance asto allow the ame to become well started without flickering or being tornaway from the burner.

After this distance, the combustion space is narrowed down to a channel,tube, slot or the like. In this constriction, the gas velocity exceedsthe flame velocity of the gas mixture and the flame is drawn out in theconstriction to a long narrow needle or sheet-liketip as indicated at 6in the gure. This constriction serves a twofold purpose in that itcontines the flame to a smaller volume, thus increasing the flametemperature in the propagation regionand it alters multitude orplurality of channels, tubes or slots 2a. 'I'his gure illustrates thatthe shape of the reaction chamber or combustionspace can be varied tosuit the particular operating conditions. In this iigure, streamlinemodiilcations of the reaction chambers are shown. The stream-line effectminimizes carbon deposition. The eluent gases containing acetylenearewithdrawn through manifold 8 or may be withdrawn independently fromeach restricted reaction chamber.

Figure III refers to an apparatus that may be resorted to when the gasvelocity'is not greater than the name velocity. Instead of resorting toa screen to prevent backring of the flame into the gas mixing device(not shown), a plurality of small nozzles 9 are provided in the burner10, 105

the nozzles being arranged in any design throughout the burner so longas there is aifairly large number of the same possessing small internaldiameters. In this figure, the burner is shown provided with twoconcentric rows of nozzles with a bailie 11 located on the face of theburner. 'I'his bale permits of the use of gas velocities approaching theame velocity, without flickering of the flame, by creatng an expansionspace in the combustion chamber 1b under the baille. The constrictedportion or reaction chamber 2c contains the needle-like or sheet-likeflame previously referred to, the flame velocity being less than the gasvelocity due to the restriction in volume of the ignited gaseousmixture. If desired, the mixed gases can be emitted from a screen whichcontains a baille, the mixing nozzle being located behind said screen.This baffle also serves to keep the base of the flame from getting tooclose to the screen (when one is used) and destroying the same.

Figures IV, V, VI and V11, inclusive, refer to certain phenomenaobserved when the initial gas velocity exceeds the flame and one or morebaflies are interposed in the gas stream. The premixed gas flows througha channel, tube, slot 12a, 12b, 12e and 12d or the like where a bailleor baiiies 13u, 13b, 13e and 13d are placed at any convenient angles tothe gas ow. In the drawings they are shown as being perpendicular to thedirection of gas flow. The baille may be placed in the center as 13a and13b or along the Wall as 13e and 13d or in any otherway. For instance, aseries or plurality of bailies may be so located that some are placedalong the wall and some away from the wall and nearer the center of thegas flow. 'I'he gas mixture passes through the channels 12a, 12b, 12eand 12d at a velocity exceeding the ame velocity of the mixture. FiguresIV and VI show how the gas stream is distorted and on the downstreamside eddies develop by the influence of the baffle or baffles. Figures Vand VII show the shapes of flames as they appear when the gas mixture isignited. 'I'hese flames keep burning by virtue of the local retardingeffect of the eddies on the gas stream. As in Figures I, I1 and III, themain part of the ame combustion occurs in a chamber in which thel lineargas velocity exceeds the flame velocity and in each figure is shown apart of the flame proper serving to maintain flame combustion.

The combination of a burner baille with a constricted reaction chambercan be utilized also with a gaseous mixture possessing an initial gasvelocity greater than the flame velocity. The reason for this is asfollows: 'Ihe flame emerges from the burner which the gas leaves at avelocity exceeding the llame velocity. Two different parts of the flamecan be distinguished. The core of the flame which we call the primaryflame is maintained by the retarding effect of the baille; It is ofred-yellow appearance. A secondary flame skirt surrounding the primaryflame appearsat a sharply limited dstance from the burner face. Thissecondary flame of a blue-red color initiates at the point at which thelinear gas velocity by lateral expansion of the gas stream becomesexactly equal to the flame velocity. As the flame is enclosed in a tubeor chamber, the secondary llame skirt is much smaller in size than if itwere unconned. The greater part of the flame burns at a gas velocityexceeding the flame velocity. By suitably constricting the confiningmeans, the secondary flame skirt can be caused to disappear completely.It is desirable to operate in the absence of the secondary llame skirtas higher yields of acetylene resultI thereby. It is our belief that thegreatest formation of acetylene takes place in the red-yellow primaryflame, especially in its narrow drawn-out part which is burning at a gasvelocity exceeding the flame velocity. The secondary flame skirts 14aand 14h in Figures V and VII also can be caused to disappear byconstricting the enveloping unit as in Figure III.

Where a constriction is resorted to, the height of the burner face abovethe constriction is conveniently made adjustable for different gasmixtures and throughput rates. A faster gas flow or a less explosivemixture naturally needs a larger space for the flame base otherwise theflame, having too small a base, ls blown out of the apparatus.

The gas mixtures are prepared in suitable mixing nozzles and fed to theburner. Where desired, a manifold is utilized to provide an evendistribution of the gas inside the burner. The exit gas-from the burnermay be cooled with water and passed on to a Cottrell precipitator whereit is freed from soot formed as a by-product. While most of the carbonis carried from the reaction chamber or chambers by the gas stream andcollected in a cooler and in the Cottrell purifier, a small amount isdeposited on the walls of the reaction chambers. This carbon is theeasier removable, the more inert gas, as nitrogen and the like, ispresent in the gas mixture. Where nitrogen is used, the carbon formed issofter and easier removable than the carbon formed using pure orsubstantially pure oxygen. In order to remove this deposit one or moreScrapers may be provided which scrapes the carbon off the walls of thechamber when operated manually or automatically at predeterminedperiods.

In order to facilitate the removal of carbon, be it carried away by thegas or scraped from the walls, the flame or flames is or areconveniently arranged to burn vertically downwards as shown in thedrawings, although the yield of acetylene is not affected by thevertical (upwards or downwards) or horizontal position of the flame.

'Ihe gas mixture, oxygen-containing gas or hydrocarbon-containing gascan be combined with other combustible gases such as hydrogen and thelike. Since the operation yields hydrogen as well as acetylene, it isdesirable, from an economic viewpoint, to recycle the same.` 'I'hepresence of hydrogen in the reaction mixture favors the yield ofacetylene in that it enables the maximum yield to be obtained at ahigher space velocity.

Gas flames with a low oxygemhydrocarbon ratio favor the formation ofacetylene. We have found it desirable to operate with a gaseous mixturecomprising hydrocarbon and oxygen, the oxygen content being less thanhalf the amount necessary for complete combustion of the hydrocarbonpresent.

As in the copending application, Serial No. 567,300, the heat ofcombustion is confined in the reaction zone as the ame burns in anoutside atmosphere created by the discharged gases of the flame. Thevarious surrounding media may comprise hydrocarbons, natural gas, carbonmonoxide, carbon dioxide, nitrogen, hydrogen or the like.

The invention is not restricted to the use of normally gaseoushydrocarbons nor to mixtures of the same, as it can be utilized withliquid hydrocarbons which have been first vaporized by any suitablemeans. Further, gases resulting from the destructive distillation ofcoal, cracked gases, by-product methane from coke-oven gas some detailthe preferred embodiment of our infractionation, hydrogenationby-product gas, etc. can be used to advantage; the presence ofinflammable gases increases the speed of the flame propagation, whereasthe presence of inert gas enhances the economy of the process.

If desired, control on the speed of propagation of the flame may beeffected through the use of an electrical field maintained in thereaction zone. f

By way of illustration only, reference will be had to certain examplesof our procedure.

Example I The apparatus shown in Figure III was used. The flow of gasesto the mixing nozzle (not shown) was 2.5 liters per minute of Californianatural gas and 1.92 liters per minute oxygen (ratio CH4/O2=1.30) 'I'heresulting gas had the following composition:

, Percent C202 7.8 CO2 4.0 CO 31.2 Hz 52.0 Olenes (02H4) 1.0 CH4 4.0

Example II The burner possessed a baffle in the burner face and theflame was enclosed in a tube of uniform diameter. A mixture of 2.5liters natural gas per minute and 1.91 liters oxygen per minute (ratioCH4/O2=1.30) was fed to the burner. The resulting gas contained 6.4%C2H2.

Example III A slot-shaped apparatus of stainless steel similar to thatshown in Figure I was used. A mixture of oxygen and natural gas (ratioCH4/O2=1.315) was introduced into the burner at a rate of 55 liters perminute. The resulting gas contained 7.2% C2H2.

Example IV The apparatus shown in Figure I was used. A mixture of 92.5ft.3 natural gas and 87.5 ft.3 oxygen-containing gas per hour (76% O2and 24% N2) was burned in the chambers (ratio CH4/O2=1.39). Aftercooling .to atmospheric temperature, an 18.5% expansion of the exit gasover the intake was observed. The composition of the exit gas was asfollows:

Per cent C2H2 6.6 CO2 4.4 CO 26.0 H2 44.5 Olenes 1.3 Paranes 7.6 N2 9.6

vention and some variants thereof, it will be understood that thisis-only for the purpose of making the invention more clear and that theinvention is not to be regarded as limited to the details of operationdescribed, nor is it dependent upon the soundness or accuracy of thetheories which we have advanced as to the reasons for theadvantageousresults attained. On the other hand, the invention is toA beregarded as limited only by the terms of the accompanying claims, inwhich it is our intention to claim all novelty inherent therein asbroadly as is possible in view of the prior art.

We claim as our invention:

1. A method' of producing acetylene which comprises subjecting a gaseousmixture containing hydrocarbon and oxygen to incomplete combustion in anenclosed apparatus, causing at least part of the gaseous mixture to flowat a linear gas velocity not greater than the flame velocity of thegaseous mixture thereby initiating flame combustion and subsequentlyincreasing the linear gas velocity to exceed the flame velocitythroughout at least the greater part of the flame While maintainingflame combustion.

2. A method of producing acetylene which comprises subjecting a gaseousmixture containing hydrocarbon and oxygen to incomplete combustion in anenclosed apparatus, the oxygen content being less than half the amountnecessary for complete combustion, causing at least part of the gaseousmixture to flow at a linear gas velocity not greater than the flamevelocity of the gaseous mixture thereby initiating flame combustion andsubsequently increasing the linear gas velocity to exceed the flamevelocity throughout at least the greater part of the flame Whilemaintaining flame combustion.

3. A method of producing acetylene which comprises subjecting a gaseousmixture containing hydrocarbon and oxygen to incomplete combustion in anenclosed apparatus at a linear gas velocity not greater than the flamevelocity of the gaseous mixture and subsequently increasing the lineargas velocity to exceed the flame velocity throughout at least thegreater part of the flame while maintaining flame combustion by part ofthe llame proper.

4. A method of producing acetylene which comprises subjecting a gaseousmixture containing hydrocarbon and oxygen to incomplete combustion in anenclosed apparatus, decreasing the initial linear gas Velocity which isvgreater than the flame velocity to one not greater than the flamevelocity whereby flame combustion is initiated and using part of theflame proper to maintain flame combustion of the gaseous mixture aftersaid mixture has had its linear gas velocity increased to exceed itsflame velocity.

5. A method of producing acetylene which comprises subjecting a gaseousmixture containing .,hydrocarbon and oxygen to incomplete combustion inan enclosed apparatus, the main portion of the combustion taking placeat a linear gas velocity greater than the flame velocity, a portion ofthe flame proper serving to maintain flame combustion.

6. A method of producing acetylene which comprises subjecting a gaseousmixture containing hydrocarbon and oxygen to incomplete combustion in anenclosed apparatus, the linear gas velocity being essentially above therespective flame Velocity of the gaseous mixture throughout at least thegreater part of the flame while maintaining flame combustion by part ofthe llame proper.

7. A method of producing acetylene which comprises flowing a gaseousmixture of hydrocarbon and oxygen, the oxygen content being insuicientfor Vcomplete combustion, in an eny closed apparatus at the ignitiontemperature o! the gaseous mixture and at a linear gas velocity notgreater than the fiame velocity and subsequently increasing the lineargas velocity to exceed the flame velocity throughout at least thegreater part of the flame While maintaining iiame combustion.

8. A method of producing acetylene which comprises flowing a gaseousmixture of hydrocarbon and oxygen at alinear gas velocity greater thanthe ame velocity, reducing the gas velocity of part of the gaseousmixture so as not to exceed the flame velocity at the ignitiontemperature of the gaseous mixture, igniting the gaseous mixture andutilizing the ignited gaseous mixture to maintain .ame combustion of theremainder of the gaseous mixture at a. linear gas velocity greater thanthe ame Velocity.

` 9. A method of producing acetylene which comprises subjecting agaseous mixture of hydrocarbon and oxygen to incomplete combustion in anenclosed apparatus at the ignition temperature of the gaseous mixture,subsequently increasing the linear gas velocity to exceed the flamevelocity throughout at least the greater drocarbon and oxygen toincomplete combustion in an enclosed apparatus while maintaining thegaseous mixture ignited, the gaseous mixture at the base of the iiamepossessing a gas velocity not greater than the ame velocity while thegaseous mixture at least at the tip of the flame possesses a. gasvelocity greater than the flame velocity.

11. A method of producing acetylene which comprises establishing andmaintaining a iiame combustion region in an enclosed apparatus, whereina 'gaseous mixture of hydrocarbon and oxygen possesses a gas velocitynot greater than the ame velocity and subsequently causing the gasvelocity to exceed the ame velocity throughout at leastthe greater partof the flame.

12. A method of producing acetylene which comprises igniting a gaseousmixture of hydrocarbon and oxygen, the oxygen content being less thanhalf the amount necessary for complete combustion, in an enclosedapparatus at a gas velocity not greater than the ame velocity andsubsequently confining the flame to a smaller volume.

HERBERT IPETER AUGUSTUS GROLL.

JAMES BURGIN.

